Track Tested: 2012 Mercedes-Benz SLK350 vs. 2009 BMW Z4 sDrive35i


When we first drove the 2012 Mercedes-Benz SLK350 back in May, we were taken by the small car's new direct-injection 3.5-liter V6. "With direct injection added, the 3.5-liter V6 is finally good enough to justify the SLK's price tag."

High praise as, traditionally, the SLK commanded a fairly high price tag. But that's not all that was different with this all-new car. The exterior has been muscled up with design language borrowed from the SLS, which results in a car much less nosey than the F1-inspired last-gen, and the suspension has been modified with firmer, adaptive damping.

Our conclusion at the end of the day was, "As soon as you stop asking the new SLK350 to be a Boxster, you can get down to the business of enjoying one of the only truly comfortable two-seat convertibles."

So it's not a Boxster. But with 302 horsepower, an as-tested price of just over $60,000, rear-drive and a power hardtop, this new SLK is awfully close to being a Z4.

The Z4 packs 300 hp and 300 pound-feet of torque from a turbocharged I6 and, in our most recent test of one, puts that to the ground via a six-speed manual -- a driver's option not available on the Merc.

So, who takes it?

Mercedes-Benz SLK350 BMW Z4 sDrive35i
0-30 (sec.): 2.2 1.9
0-45 (sec.): 3.7 3.6
0-60 (sec.): 5.6 5.2
0-60 with 1-ft Rollout (sec.): 5.4 4.9
0-75 (sec.): 8.1 7.9
1/4-mile (sec @ mph): 13.8 @ 100.9 13.4 @ 103.7
30-0 (ft): 28 26
60-0 (ft): 113 106
Skid pad lateral accel (g): 0.87 0.87
Slalom: 66.2 68.9

Vehicle: 2012 Mercedes-Benz SLK350
Odometer: 1,870
Date: 8-2-2011
Driver: Mike Monticello
Price: $65,875

Specifications:

Transmission Type: Seven-speed automatic
Engine Type: Longitudinal, Naturally aspirated V6 with direct injection
Displacement (cc/cu-in): 3,498/218
Redline (rpm): 6,250
Horsepower (hp @ rpm): 302 @ 6,500
Torque (lb-ft @ rpm): 273 @ 3,500 - 5,250
Brake Type (front): 13.5-by-1.3-inch ventilated discs with two-piston sliding calipers
Brake Type (rear): 11.8-by-0.4-inch ventilated discs with single-piston sliding calipers
Suspension Type (front): Independent MacPherson struts, coil springs, driver-adjustable two-mode variable dampers, lateral links, stabilizer bar
Suspension Type (rear): Independent multilink, coil springs, driver-adjustable two-mode variable dampers, stabilizer bar
Tire Size (front): 225/40 R18 (92Y)
Tire Size (rear): 245/35 R18 (92Y)
Tire Brand: Continental
Tire Model: ContiSport Contact 5
Tire Type: Summer performance
As tested Curb Weight (lb): 3,405

Test Results:

Acceleration
0-30 (sec): 2.2 (2.2 w/TC off)
0-45 (sec): 3.7 (3.7 w/TC off)
0-60 (sec): 5.6 (5.6 w/TC off)
0-60 with 1-ft Rollout (sec): 5.3 (5.4 w/TC off)
0-75 (sec): 8.0 (8.1 w/TC off)
1/4-Mile (sec @ mph): 13.8 @ 101.3 (13.8 @ 100.9 w/TC off)

Braking:
30-0 (ft): 28
60-0 (ft): 113

Handling
Slalom (mph): 66.2 ( 64.4 with TC on)
Skid Pad Lateral acceleration (g): 0.87 ( 0.86 with TC on )

Db @ Idle: 48.2
Db @ Full Throttle: 79.4
Db @ 70 mph Cruise: 67.5

DB @ 70 with top down: 72.9

Acceleration: Good punch right off the line, no hesitation, jerks your neck back the throttle is so abrupt. Oddly, was difficult to match the first run, when ESC was on and tranmission was in "E" mode, as opposed to Sport or Manual. Power braking did little to improve times. Manual shifting is via paddles or console lever (slap left for downshifts). Blips throttle on downshifts. Shifts at 6,800 rpm regardless of tranny mode.

Braking: Perfectly controlled panic braking and very firm pedal with short travel. Extremely reassuring, and incredibly consistent and short stopping distances. No fade.

Handling:

Skid pad: The little SLK is actually quite controllable, the chassis is very willing to let you play with the throttle to adjust the line and control understeer. Unfortunately the throttle calibration makes it easy to overshoot the desired amount of throttle each time you reapply. ESC hardly detectable at all here when switched on.

Slalom: Fairly nimble little car, nice and narrow and low to the ground. Steering is quick enough but lacks feel. Tires have decent grip. Couple of hindrances to a better time: The suspension is quite springy, rebounding oddly after each turn. The other problem is the annoyingly abrupt throttle (possibly due to the direct injection?), which always comes back on with too much force, upsetting the car's attitude. ESC cuts throttle (when on) if you get aggressive.

Vehicle: 2009 BMW Z4 sDrive35i
Odometer: 1,530
Date: 5-12-2009
Driver: Josh Jacquot
Price: $64,020

Specifications:
Drive Type: Rear-wheel drive
Transmission Type: Six-speed manual
Engine Type: Longitudinal inline-6 with twin-turbochargers and direct injection
Displacement (cc/cu-in): 2,979/182
Redline (rpm): 7,000
Horsepower (hp @ rpm): 300 hp @ 5,800 rpm
Torque (lb-ft @ rpm): 300 lb-ft @ 1,400 rpm
Brake Type (front): 13.7-inch ventilated discs with single-piston sliding calipers
Brake Type (rear): 12.8-inch ventilated discs with single-piston sliding calipers
Suspension Type (front): Independent, MacPherson struts, coil springs and stabilizer bar
Suspension Type (rear): Independent, multilink, coil springs and stabilizer bar
Tire Size (front): 224/40R18 88W
Tire Size (rear): 255/35R18 90W
Tire Brand: Bridgestone
Tire Model: Potenza RE050A
Tire Type: Summer Performance
As tested Curb Weight (lb): 3,495

Test Results:
0-30 (sec): 1.9 (2.2 with TC on)
0-45 (sec): 3.6 (3.8 with TC on)
0-60 (sec): 5.2 (5.5 with TC on)
0-60 with 1-ft Rollout (sec): 4.9 (5.2 with TC on)
0-75 (sec): 7.7 (8.1 with TC on)
1/4-Mile (sec @ mph): 13.4 @ 103.7 (13.7 @ 103 with TC on)

30-0 (ft): 26
60-0 (ft): 106
Slalom (mph): 68.9 (67.4 stability control on)
Skid Pad Lateral acceleration (g): 0.87g ( 0.86 with TC on )

Db @ Idle: 47.9
Db @ Full Throttle: 79.1
Db @ 70 mph Cruise: 68.7

DB @ 70 with top down: 82.6

Acceleration: As with all BMWs using this engine, the Z4 is hard to launch effectively. It wants to boil or bog. Get it right speedwise and there's lots of wheel hop, but it's quick.

Braking: Solid, consistent pedal on all stops. Completely confidence-inspiring.

Handling:

Skid pad: Will not rotate regardless of throttle/steering inputs -- at the speeds reached on a 100-foot-radius skid pad, anyway. Just manage the understeer.

Slalom: Very stable during high-speed transitions. Not sensitive to the bump at cone #3. Good information through controls, but not nimble in this maneuver.

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